Low insertion force electrical connectors for making electrical connections between printed circuit boards are well known in the industry. Examples of these types of connectors are disclosed in U.S. Pat. Nos. 3,795,888; 3,848,952; 3,920,303; 4,136,917; 4,185,882; 4,575,172; and 4,737,120. The connectors disclosed in these patents are of the type which have a pair of spring contacts which allow insertion of the printed circuit boards into contact areas of the connectors under reduced insertion force conditions.
Many of these prior art connectors are provided with contacts which have a steep force/deflection curve. Consequently, the spring contacts can easily take a permanent set even if the contacts are displaced only a small amount. Therefore, there is a strong likelihood that the insertion of a wide daughter board into the connector will cause the contacts to take a permanent set. The connector is thereby rendered ineffective when the wide board is replaced by a relatively narrow board.
U.S. Pat. No. 4,737,120 teaches of a contact which has a low spring rate or a shallow force/deflection curve. This allows the contacts to have a large tolerance to the thickness of the daughter board, thereby preventing the contacts from taking a permanent set as the daughter board is inserted between the contact areas of the contacts. However, even in a connector which has contacts with a low spring rate, it is conceivable that as the daughter board is brought into engagement with the contacts, the daughter board may damage the contacts, causing the contacts to take a permanent set. This problem is magnified when the daughter board is misaligned with the opening provided between the contact areas of the contacts.
It would therefore be beneficial to provide a connector which has contacts which have means to prevent overstress of the contacts, even when the daughter board is improperly inserted into the connector.